Twisted metal bar for reinforced concrete construction



H. K. DYSQN. TWISTED METAL BA R REIN ED CONCRETE CONSTUCTION. AP TION Fl UV. 161 1920.

1 $599,701 Patented 'Dec. 6, 1921..

UNITED STATES TWISTED METAL BAR FOB EEEENFORCED CONCRETE CONSTRUCTION.

sen-e0 1 Specification of Letters Patent. 1

Patented Dec. 6, rear.

Application filed. November 16, 1920. serial No. 424,495.

To all whom it may concern:

Be it known that l, HERBERT Knnrrron Drson, a subject of the King of Great Britain, residing at 17 \Varwick Square, i/l estininster, London, S. WV. 1, England, have invented certain new and useful linoprovements in Twisted Metal Bars for Heinforced Concrete Construction, of which the following is a specification.

This invention relates to twisted metal bars for use as reinforcement in concrete construction.

little as possible from the circle; but it is necessary to provide some departure from i the circular form in order that the twist oi the bar may be readily detected.

In accordance with my invention 1 provide a section of bar consisting substantially ot a circle provided with a single flat side, depression or protuberance. Thishas the advantage of securing. a small departure from the circular term and of giving a form of section which enables the twisting operation readily to be performed after the rolling or drawing operation.

to the chord is nearly equal to the diameter of the circle and the departure from the circular form is indicated by the dotted line. In the form shown in Fig. 2 the req uisite width of the flat side 6 is obtained without so much diminution in depth of the section by allowing the metal to How sidewise into the section shown, the initial circular :t'orni being indicated by the dotted lines.

in the gripping dies for the twisting operation illustrated in Fig.8 the lower sur- -face c or the die is of semicircular or other circular arcuate form, and the bar is gripped against it by means of a key (Z provided with a suitable head to facilitate withdrawn in the form illustrated in Fig. 4, the

lower die is of curved but not of circular contour giving contact at two polnts. This term has the advantage that 1t glves a better grip and that the same die can be employed for bars of slightly different diameter.

it is to be understood that the surface Z) need not be flat but may comprise any suitable single depression or protuberance, the lower surtace ot the key (Z being correspondingly contoured.

What i claim is:

l. A twisted metal bar for reinforced concrete construction having a cross sectional profile, consisting of a circular outline with a comparatively small interrupted portion cit-a non-conforming plane, the interrupted portion following a spiral line throughout the length of the bar.

rt. twisted metal bar having a trans verse section of circular form interrupted by a flat portion of a limited chord length, the flat portion defining a spiral throughout the length of the bar.

In testimony whereof I atlix my signature.

HERBERT KEMPTON DYSON. 

